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Re: ZFS on rpi3




On 23/02/2020 8:08 pm, Sad Clouds wrote:
On Sun, 23 Feb 2020 09:08:46 +1100
MJ <mafsys1234%gmail.com@localhost> wrote:

On 23/02/2020 1:12 am, Sad Clouds wrote:
I'm trying out NetBSD-9 with ZFS on raspberry pi 3. I have 128GB
USB SD card which has ZFS setup. Noticed that sometimes when under
heavy use something goes wrong and pgdaemon spins on CPU 100% all
the time.

Not sure if this is something to do with small amount of RAM on this
machine. Are there any tunables like in FreeBSD

vm.kmem_size="330M"
vm.kmem_size_max="330M"
vfs.zfs.arc_max="40M"
vfs.zfs.vdev.cache.size="5M"

that make ZFS play nice when low on RAM? Looked at "sysctl -a" but
there are only kstat parameters, I assume they are only for
statistics and don't affect run-time?

ZFS on Raspberry Pi? Nope. Not enough memory. Stick to FFS.

Even a Pi 4 still doesn't have enough, unless all you want to use it
for is run ZFS and NOTHING else.


Yeah, I noticed at lot of system issues/crashes with ZFS on rpi3, so
far FFS has been pretty stable. Although I do have 4GiB rpi4, not
tried it with ZFS yet, but I would have thought that this amount of
RAM would have been sufficient. I've seen some references on the net
that state 8GiB is the minimum, however I have 2GiB NetBSD VM in a
VirtualBox with ZFS configured and not seen any issues over the last
few days of random testing.

I really don't see any benefit to it over FFS. Sure CoW is good but really, for a pi? If the data's that important I would not be putting it on a pi.

The benefits of ZFS, like expandable volumes, no need for fstab, RAID etc just to name a few, all seem lost to me on a Pi. If you use it, you're wasting a lot of RAM on just its L2Arc.

No, I'm not convinced of its usefulness on such a device, given FFS is more than likely a lot faster (but more likely to lose your data, statistically)

I'm also fairly certain the rpi4 is not functional under NetBSD yet. I may be wrong.





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